Li+ Shuttle bus enables safe fast ion transport in solid polymer electrolytes

Solid polymer electrolytes are important for lithium metal batteries, but their limited Li + transference efficiency hinders large-scale deployment. Here we report a Li⁺ shuttle bus strategy that immobilizes anions at one-dimensional charged interface, promotes lithium salt dissociation, and guides Li⁺ enrichment. The effect of Coulombic repulsion among densely coordinated Li⁺ species weakens solvation structure for Li + , achieving fast, collective and one-dimensional ion shuttling at the microscopic scale. Consequently, the designed solid polymer electrolyte exhibits a high ionic conductivity of 0.92 × 10 −3 S cm −1 at 28 °C. Li | |LiFePO 4 cells operate nearly 5000 cycles at 5 C and maintain 77% capacity after 900 cycles at −40 °C. Li | |LiNi 0.8 Co 0.1 Mn 0.1 O 2 pouch cell further realizes high specific energy (508 Wh kg −1 , 200 cycles, 95.2% retention). This work establishes a Li⁺ shuttle-bus strategy for constructing solid polymer electrolytes with fast-charging capability and wide-temperature adaptability, offering findings into the design of solid-state lithium metal batteries.